code: def _reduce_op_to_function(self, op):
      if op == ReduceOp.SUM:
          return torch.sum
  
      raise NotImplementedError()
  
imports: import logging
  import threading
  from operator import itemgetter
  from queue import Queue
  import torch
  from torch.distributed import ReduceOp
  from .communicator import Communicator
label_desc: Use image node_id 12 for calling the InProcessCommunicator obj's underlying member method code with example usage: obj._reduce_op_to_function(op) and returns: torch